[GH-6698][FOLLOWUP] Fix build of DeepLearningSHAPTest on Java 13+

[mn-mikke]

GH-6698

Java versions 13+ have problems to compile large try statement section:

[2023-10-12T15:49:56.532Z] > Task :h2o-algos:compileTestJava

[2023-10-12T15:49:56.532Z] /home/jenkins/slave_dir_from_mr-0xc1/workspace/2o-3-nightly-pipeline_rel-3.44.0/java-13-smoke/h2o-3/h2o-algos/src/test/java/hex/deeplearning/DeepLearningSHAPTest.java:1677: error: code too large for try statement

[2023-10-12T15:49:56.532Z]     try {

[2023-10-12T15:49:56.532Z]         ^

[2023-10-12T15:49:56.532Z] /home/jenkins/slave_dir_from_mr-0xc1/workspace/2o-3-nightly-pipeline_rel-3.44.0/java-13-smoke/h2o-3/h2o-algos/src/test/java/hex/deeplearning/DeepLearningSHAPTest.java:1668: error: code too large

[2023-10-12T15:49:56.532Z]   public void testClassificationTanhDeepSHAPComparison() {

[2023-10-12T15:49:56.532Z]               ^

I suggest to separate asserts to a dedicated method. This approach works fixed the problem locally.